Patent GB-1370850-A (GB)
Title: Illuminated indicating devices
IPC: H03J1/02
Filed: 1972-05-15
Abstract: 1370850 Radio receiver indicator, transistor bi-stable and multistable circuits BLAUPUyKTWEBKE GmbH 15 May 1972 [13 May 1971] 22732/72 Headings H3Q and H3T [Also in Division G4] In an indicating device comprising a series circuit including a succession of luminous elements L, Fig. 1, arranged to be connected across a voltage supply having two terminals 10, 11 at different potentials, the junction between each two successive elements is provided with a switch S for connecting the junction to one or other of the potentials and the switches are connected together so that switches preceding a switch connected to one of the potentials are connected to the other of the potentials and switches succeeding the switch are connected to the one of the potentials to apply the different potentials across the luminous element immediately preceding the switch being considered. A tuning voltage for an electronically tunable receiver is applied to a terminal 30 of a control section 29, Fig. 2, which is described in detail in (Fig. 4, not shown). The tuning voltage at 30 is compared in a differential amplifier (45, 46) with a voltage on a monitoring line 26 indicating the operated switch S1-S9. The control signal output on control line 28, e.g. corresponding to the luminous element L5 such as a lamp or luminescent diode, is applied to the switches so that the outputs 22 of the switches S1-S4 are placed at the first potential 10 (100) and the switches S5-S9 are at the second potential 11 (101). The coupling of terminals 24 to 25 and of terminals 23 and 22 between the switches S enables only the first switch in the series which at the time has a positive potential at its output 22 to change state in response to a negative potential applied to line 28. Also only the last switch in the series which at the time has a negative potential at its output 22 is able to change state in response to a positive potential applied to line 28. Therefore only one pair of adjacent switches have different potentials on their outputs 22 at any time so applying a potential difference across the corresponding luminous element. The position of this potential difference may be moved stepwise forwards or backwards by negative or positive potentials on line 28 to move the position of energization in the series of luminous elements. The indicating device may be largely in the form of an integrated circuit. Each switch S1-S9 may be as shown in the bi-stable circuit of Fig. 3. Diodes 38 and 39 provide the appropriate coupling between the terminals 24, 25 and 23, 22 of the switches. In the absence of any control signal on line 28 the switch S provides a positive output at 22. Transistors 31 and 33 are on and 32 and 34 are off as are diodes 38, 39. A negative input to the control input 27 turns transistor 33 off, transistors 34 and 32 turn on and transistor 31 turns off so as to make the output 22 negative. In a modification (Fig. 5, not shown) each switch S is formed of OR gate (60) and an AND gate (61). In a further modification (Fig. 6, not shown) each switch is formed of two negating OR-gates (NOR gates 70, 71) and an inverter stage (72).